[es6] Implement spec compliant ToPrimitive in the runtime.

src/execution.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_EXECUTION_H_
 #define V8_EXECUTION_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/handles.h"
@@ skipping 41 matching lines @@
   // any thrown exceptions. The return value is either the result of
   // calling the function (if caught exception is false) or the exception
   // that occurred (if caught exception is true).
   // In the exception case, exception_out holds the caught exceptions, unless
   // it is a termination exception.
   static MaybeHandle<Object> TryCall(Handle<JSFunction> func,
                                      Handle<Object> receiver, int argc,
                                      Handle<Object> argv[],
                                      MaybeHandle<Object>* exception_out = NULL);
 
-  // ECMA-262 9.3
-  MUST_USE_RESULT static MaybeHandle<Object> ToNumber(
-      Isolate* isolate, Handle<Object> obj);
-
   // ECMA-262 9.4
   MUST_USE_RESULT static MaybeHandle<Object> ToInteger(
       Isolate* isolate, Handle<Object> obj);
 
   // ECMA-262 9.5
   MUST_USE_RESULT static MaybeHandle<Object> ToInt32(
       Isolate* isolate, Handle<Object> obj);
 
   // ECMA-262 9.6
   MUST_USE_RESULT static MaybeHandle<Object> ToUint32(
       Isolate* isolate, Handle<Object> obj);
 
 
   // ES6, draft 10-14-14, section 7.1.15
   MUST_USE_RESULT static MaybeHandle<Object> ToLength(
       Isolate* isolate, Handle<Object> obj);
 
   // ECMA-262 9.8
-  MUST_USE_RESULT static MaybeHandle<Object> ToString(
-      Isolate* isolate, Handle<Object> obj);
-
-  // ECMA-262 9.8
   MUST_USE_RESULT static MaybeHandle<Object> ToDetailString(
       Isolate* isolate, Handle<Object> obj);
 
   // ECMA-262 9.9
   MUST_USE_RESULT static MaybeHandle<Object> ToObject(
       Isolate* isolate, Handle<Object> obj);
 
   // Create a new date object from 'time'.
   MUST_USE_RESULT static MaybeHandle<Object> NewDate(
       Isolate* isolate, double time);
@@ skipping 193 matching lines @@
   friend class Isolate;
   friend class StackLimitCheck;
   friend class PostponeInterruptsScope;
 
   DISALLOW_COPY_AND_ASSIGN(StackGuard);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_EXECUTION_H_